/**
 * TextAreaExpander plugin for jQuery
 * v1.0
 * Expands or contracts a textarea height depending on the
 * quatity of content entered by the user in the box.
 *
 * By Craig Buckler, Optimalworks.net
 *
 * As featured on SitePoint.com:
 * http://www.sitepoint.com/blogs/2009/07/29/build-auto-expanding-textarea-1/
 *
 * Please use as you wish at your own risk.
 */

/**
 * Usage:
 *
 * From JavaScript, use:
 *     $(<node>).TextAreaExpander(<minHeight>, <maxHeight>);
 *     where:
 *       <node> is the DOM node selector, e.g. "textarea"
 *       <minHeight> is the minimum textarea height in pixels (optional)
 *       <maxHeight> is the maximum textarea height in pixels (optional)
 *
 * Alternatively, in you HTML:
 *     Assign a class of "expand" to any <textarea> tag.
 *     e.g. <textarea name="textarea1" rows="3" cols="40" class="expand"></textarea>
 *
 *     Or assign a class of "expandMIN-MAX" to set the <textarea> minimum and maximum height.
 *     e.g. <textarea name="textarea1" rows="3" cols="40" class="expand50-200"></textarea>
 *     The textarea will use an appropriate height between 50 and 200 pixels.
 */

(function($) {

  // jQuery plugin definition
  $.fn.TextAreaExpander = function(minHeight, maxHeight) {

    var hCheck = !($.browser.msie || $.browser.opera);

    // resize a textarea
    function ResizeTextarea(e) {

      // event or initialize element?
      e = e.target || e;

      // find content length and box width
      var vlen = e.value.length, ewidth = e.offsetWidth;
      if (vlen != e.valLength || ewidth != e.boxWidth) {

        if (hCheck && (vlen < e.valLength || ewidth != e.boxWidth)) e.style.height = "0px";
        var h = Math.max(e.expandMin, Math.min(e.scrollHeight, e.expandMax));

        e.style.overflow = (e.scrollHeight > h ? "auto" : "hidden");
        e.style.height = h + "px";

        e.valLength = vlen;
        e.boxWidth = ewidth;
      }

      return true;
    };

    // initialize
    this.each(function() {

      // is a textarea?
      if (this.nodeName.toLowerCase() != "textarea") return;

      // set height restrictions
      var p = this.className.match(/expand(\d+)\-*(\d+)*/i);
      this.expandMin = minHeight || (p ? parseInt('0'+p[1], 10) : 0);
      this.expandMax = maxHeight || (p ? parseInt('0'+p[2], 10) : 99999);

      // initial resize
      ResizeTextarea(this);

      // zero vertical padding and add events
      if (!this.Initialized) {
        this.Initialized = true;
        $(this).css("padding-top", 0).css("padding-bottom", 0);
        $(this).bind("keyup", ResizeTextarea).bind("focus", ResizeTextarea);
      }
    });

    return this;
  };

})(jQuery);


// initialize all expanding textareas
jQuery(document).ready(function() {
  jQuery("textarea[class*=expand]").TextAreaExpander();
});
